diff --git a/src/OpenClaw.Shared/MenuSizingHelper.cs b/src/OpenClaw.Shared/MenuSizingHelper.cs
new file mode 100644
index 0000000..72db271
--- /dev/null
+++ b/src/OpenClaw.Shared/MenuSizingHelper.cs
@@ -0,0 +1,28 @@
+namespace OpenClaw.Shared;
+
+/// <summary>
+/// Pure helper methods for constraining popup menu size to the visible work area.
+/// </summary>
+public static class MenuSizingHelper
+{
+    public static int ConvertPixelsToViewUnits(int pixels, uint dpi)
+    {
+        if (pixels <= 0) return 0;
+        if (dpi == 0) dpi = 96;
+
+        return Math.Max(1, (int)Math.Floor(pixels * 96.0 / dpi));
+    }
+
+    public static int CalculateWindowHeight(int contentHeight, int workAreaHeight, int minimumHeight = 100)
+    {
+        if (contentHeight < 0) contentHeight = 0;
+        if (minimumHeight < 1) minimumHeight = 1;
+
+        if (workAreaHeight <= 0)
+            return Math.Max(contentHeight, minimumHeight);
+
+        var minimumVisibleHeight = Math.Min(minimumHeight, workAreaHeight);
+        var desiredHeight = Math.Max(contentHeight, minimumVisibleHeight);
+        return Math.Min(desiredHeight, workAreaHeight);
+    }
+}
diff --git a/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml b/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml
index 11828ff..885ccd1 100644
--- a/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml
+++ b/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml
@@ -14,7 +14,9 @@
             BorderBrush="{ThemeResource SurfaceStrokeColorDefaultBrush}"
             BorderThickness="1"
             CornerRadius="8">
-        <ScrollViewer VerticalScrollBarVisibility="Auto">
+        <ScrollViewer VerticalScrollBarVisibility="Visible"
+                      VerticalScrollMode="Enabled"
+                      HorizontalScrollBarVisibility="Disabled">
             <StackPanel x:Name="MenuPanel" Padding="4,6">
                 <!-- Menu items will be added programmatically -->
             </StackPanel>
diff --git a/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml.cs b/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml.cs
index 7ce7565..7b486a1 100644
--- a/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml.cs
+++ b/src/OpenClaw.Tray.WinUI/Windows/TrayMenuWindow.xaml.cs
@@ -1,6 +1,7 @@
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Input;
+using OpenClaw.Shared;
 using OpenClawTray.Helpers;
 using System;
 using System.Runtime.InteropServices;
@@ -37,6 +38,9 @@ public sealed partial class TrayMenuWindow : WindowEx
     [DllImport("user32.dll")]
     private static extern uint GetDpiForWindow(IntPtr hwnd);
 
+    [DllImport("Shcore.dll")]
+    private static extern int GetDpiForMonitor(IntPtr hmonitor, MonitorDpiType dpiType, out uint dpiX, out uint dpiY);
+
     [DllImport("user32.dll")]
     private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
 
@@ -66,6 +70,11 @@ private struct MONITORINFO
         public RECT rcWork;
         public uint dwFlags;
     }
+
+    private enum MonitorDpiType
+    {
+        MDT_EFFECTIVE_DPI = 0
+    }
     #endregion
 
     public event EventHandler<string>? MenuItemClicked;
@@ -147,8 +156,7 @@ public void ShowAtCursor()
             if (menuWidthPx <= 0 || menuHeightPx <= 0)
             {
                 var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
-                uint dpi = GetDpiForWindow(hwnd);
-                if (dpi == 0) dpi = 96;
+                uint dpi = GetEffectiveMonitorDpi(hMonitor, hwnd);
                 double scale = dpi / 96.0;
                 menuWidthPx = (int)(280 * scale);
                 menuHeightPx = (int)(_menuHeight * scale);
@@ -284,8 +292,67 @@ public void SizeToContent()
         // Separators: ~13px each  
         // Headers: ~30px each
         // Plus padding: ~16px
-        _menuHeight = (_itemCount * 36) + (_separatorCount * 13) + (_headerCount * 30) + 16;
-        _menuHeight = Math.Max(_menuHeight, 100); // minimum
+        var contentHeight = (_itemCount * 36) + (_separatorCount * 13) + (_headerCount * 30) + 16;
+        _menuHeight = Math.Max(contentHeight, 100); // minimum
+
+        if (TryGetCurrentMonitorMetrics(out var workAreaHeightPx, out var dpi))
+        {
+            // Constrain the popup to the visible work area so the ScrollViewer gets
+            // a viewport and the menu stays reachable near the tray/taskbar.
+            var workAreaHeight = MenuSizingHelper.ConvertPixelsToViewUnits(workAreaHeightPx, dpi);
+            _menuHeight = MenuSizingHelper.CalculateWindowHeight(contentHeight, workAreaHeight);
+        }
+
         this.SetWindowSize(280, _menuHeight);
     }
+
+    private bool TryGetCurrentMonitorMetrics(out int workAreaHeight, out uint dpi)
+    {
+        workAreaHeight = 0;
+        dpi = 96;
+
+        if (!GetCursorPos(out POINT pt))
+            return false;
+
+        var hMonitor = MonitorFromPoint(pt, MONITOR_DEFAULTTONEAREST);
+        if (hMonitor == IntPtr.Zero)
+            return false;
+
+        var monitorInfo = new MONITORINFO { cbSize = Marshal.SizeOf<MONITORINFO>() };
+        if (!GetMonitorInfo(hMonitor, ref monitorInfo))
+            return false;
+
+        workAreaHeight = monitorInfo.rcWork.Bottom - monitorInfo.rcWork.Top;
+        var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
+        dpi = GetEffectiveMonitorDpi(hMonitor, hwnd);
+        return workAreaHeight > 0;
+    }
+
+    private static uint GetEffectiveMonitorDpi(IntPtr hMonitor, IntPtr hwnd)
+    {
+        if (hMonitor != IntPtr.Zero)
+        {
+            try
+            {
+                var hr = GetDpiForMonitor(hMonitor, MonitorDpiType.MDT_EFFECTIVE_DPI, out var dpiX, out var dpiY);
+                if (hr == 0)
+                {
+                    if (dpiY != 0)
+                        return dpiY;
+
+                    if (dpiX != 0)
+                        return dpiX;
+                }
+            }
+            catch (DllNotFoundException)
+            {
+            }
+            catch (EntryPointNotFoundException)
+            {
+            }
+        }
+
+        var dpi = hwnd != IntPtr.Zero ? GetDpiForWindow(hwnd) : 0;
+        return dpi == 0 ? 96u : dpi;
+    }
 }
diff --git a/tests/OpenClaw.Tray.Tests/MenuPositionerTests.cs b/tests/OpenClaw.Tray.Tests/MenuPositionerTests.cs
index 0249c3f..131cea6 100644
--- a/tests/OpenClaw.Tray.Tests/MenuPositionerTests.cs
+++ b/tests/OpenClaw.Tray.Tests/MenuPositionerTests.cs
@@ -82,6 +82,45 @@ public void TaskbarAtBottom_TypicalScenario()
             $"Menu bottom edge {y + MenuHeight} should not exceed work area bottom 1040");
     }
 
+    [Fact]
+    public void OversizedMenuHeight_IsClampedToWorkAreaHeight()
+    {
+        const int oversizedMenuHeight = 1200;
+        var visibleHeight = MenuSizingHelper.CalculateWindowHeight(
+            oversizedMenuHeight,
+            WorkBottom - WorkTop);
+
+        Assert.Equal(WorkBottom - WorkTop, visibleHeight);
+    }
+
+    [Fact]
+    public void PixelHeight_IsConvertedToViewUnits_UsingDpi()
+    {
+        var viewHeight = MenuSizingHelper.ConvertPixelsToViewUnits(1200, 192);
+        Assert.Equal(600, viewHeight);
+    }
+
+    [Fact]
+    public void OversizedMenuNearTray_WithClampedHeight_RemainsFullyVisibleWithinWorkArea()
+    {
+        // Regression test for the tray popup overflow bug:
+        // the popup height must be constrained before positioning so the
+        // ScrollViewer can handle overflow within the visible work area.
+        const int oversizedMenuHeight = 1200;
+        var visibleHeight = MenuSizingHelper.CalculateWindowHeight(
+            oversizedMenuHeight,
+            WorkBottom - WorkTop);
+
+        var (_, y) = MenuPositioner.CalculatePosition(
+            1800, 1060, MenuWidth, visibleHeight,
+            WorkLeft, WorkTop, WorkRight, WorkBottom);
+
+        Assert.True(y >= WorkTop, $"Menu Y {y} should not be above the work area top {WorkTop}");
+        Assert.True(
+            y + visibleHeight <= WorkBottom,
+            $"Menu bottom edge {y + visibleHeight} should not exceed work area bottom {WorkBottom}");
+    }
+
     [Fact]
     public void TaskbarAtRight_Scenario()
     {
diff --git a/tests/OpenClaw.Tray.Tests/TrayMenuWindowMarkupTests.cs b/tests/OpenClaw.Tray.Tests/TrayMenuWindowMarkupTests.cs
new file mode 100644
index 0000000..12b7214
--- /dev/null
+++ b/tests/OpenClaw.Tray.Tests/TrayMenuWindowMarkupTests.cs
@@ -0,0 +1,40 @@
+using System.Text.RegularExpressions;
+
+namespace OpenClaw.Tray.Tests;
+
+public class TrayMenuWindowMarkupTests
+{
+    [Fact]
+    public void TrayMenuWindow_UsesVisibleVerticalScrollbar()
+    {
+        var xamlPath = Path.Combine(
+            GetRepositoryRoot(),
+            "src",
+            "OpenClaw.Tray.WinUI",
+            "Windows",
+            "TrayMenuWindow.xaml");
+
+        var xaml = File.ReadAllText(xamlPath);
+
+        Assert.Matches(
+            new Regex(@"<ScrollViewer[^>]*VerticalScrollBarVisibility=""Visible""", RegexOptions.Singleline),
+            xaml);
+    }
+
+    private static string GetRepositoryRoot()
+    {
+        var directory = new DirectoryInfo(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "moltbot-windows-hub.slnx")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "src")))
+            {
+                return directory.FullName;
+            }
+
+            directory = directory.Parent;
+        }
+
+        throw new InvalidOperationException("Could not find repository root.");
+    }
+}